Support placing new symbols in a separate module about maybe-async-cfg

[nvksv]

I just updated the crate to version 0.2.1. The maybe attribute now can be applied to modules. E.g.:

crates.toml

[package]
name = "maybe-async-cfg-test-1"
version = "0.1.0"
edition = "2021"

[features]
sync = []
async = []
default = ["sync", "async"]

[dependencies]
maybe-async-cfg = "0.2.1"

main.rs

#[maybe_async_cfg::maybe(
    idents(hello_world(fn,keep)),
    sync(feature="sync",keep_self), 
    async(feature="async",self="async_")
)]
pub mod blocking {
  pub async fn hello_world() {
    todo!()
  }
}

fn main() {
    println!("Hello, world!");
}

now is expanding (cargo expand) into

#![feature(prelude_import)]
#[prelude_import]
use std::prelude::rust_2021::*;
#[macro_use]
extern crate std;
#[cfg(feature = "sync")]
pub mod blocking {
    pub fn hello_world() {
        ::core::panicking::panic("not yet implemented")
    }
}
#[cfg(feature = "async")]
pub mod async_ {
    pub async fn hello_world() {
        ::core::panicking::panic("not yet implemented")
    }
}
fn main() {
    {
        ::std::io::_print(::core::fmt::Arguments::new_v1(&["Hello, world!\n"], &[]));
    };
}

Earlier, this required reimport:

#[cfg(feature = "async")]
pub mod async_ftp {
    pub use crate::ftp::FtpStreamAsync as FtpStream;
}
#[cfg(feature = "sync")]
pub mod sync_ftp {
    pub use crate::ftp::FtpStreamSync as FtpStream;
}

Thank you for good idea!

[quentinmit]

Why does your example require specifying hello_world in idents?

I actually already implemented this as well... https://github.com/quentinmit/maybe-async-cfg/tree/mod

and I didn't find any need to specify idents.

[nvksv]

Yes, if the name of hello_world should not change, it is not necessary to specify it in idents.

My mistake. Initially, I tested on the example when the hello_world was supposed to turn into a hello_world_async/hello_world_sync, and then quickly banned such renaming. But it would be more correct to delete idents(hello_world(fn)) entirely, as you noticed.